Photoelectrostatic recording member

ABSTRACT

A photoelectrostatic copy sheet is prepared by using a paper base sheet having a roughness in the range of from 100 to 250 Sheffield units. Bonded to the rough surfaced paper is a photoconductive layer comprising zinc oxide and in another embodiment sub-millimicron sized particles of hydrophobic silica dispersed in a resin binder. The layer conforms to the rough fiber textured surface of the base sheet to provide a finished recording surface having a roughness in the range of from 70 to 250 Sheffield units and a gloss (75*, Gardner) not in excess of 20 percent. This sheet has the appearance, feel and handle of an uncoated piece of paper.

United States Patent Bornarth et a1.

[ 51 Mar. 28, 1972 [54] PHOTOELECTROSTATIC RECORDING MEMBER [72]Inventors: Dennis M. Bornarth, Palatine; Frank Schneidinger, Marengo,both of 111.

[73] Assignee: Addressograph-Multigraph Corporation,

Mount Prospect, Ill.

[22] Filed: Apr. 20, 1970 [21] Appl. No.: 30,238

Related 1.1.8. Application Data [63] Continuation-impart of Ser. No.664,958, Sept. 1,

1967, abandoned.

[52] U.S.Cl ..96/l.8, 252/501, 117/76 P, 117/201, 117/218, 101/462 51]Int. Cl. ..G03g 5/08 [58] Field ofSearch ..96/1.5, 1.6, 1.7, 1.8;252/501; 117/76, 56,155, 201, 215, 218

[56] References Cited UN lTED STATES PATENTS 3,241,958 3/1966 Bornarthet a1 ..96/1.8 3,481,734 12/1969 Bornarth ..96/l 2,230,981 2/1941 Tolandet a]... 96/33 X 3,079,253 2/1963 Greig ..96/1.8

3,155,503 11/1964 Cassiers et a1. ..96/1.5 3,165,458 1/1965 Harriman..96/1 .8 X 3,234,017 2/1966 Hey] et a1 ..96/1 3,281,240 10/1966Cassiers et a1. ..96/1.5 3,298,831 l/1967 Lau et a1 ..96/1.8 X 3,345,16210/1967 McFarlane et a1 ..96/1.8 3,347,670 10/1967 Nelson et al ..96/l.53,376,134 4/1968 Stahly et a1. .....96/1.8 3,378,370 4/1968 Brancato..96/l.8 3,399,060 8/1968 Clang ..96/1.8 X

Primary Examiner-Charles E. Van Horn Attorney-Sol L. Goldstein [57]ABSTRACT A photoelectrostatic copy sheet is prepared by using a paperbase sheet having a roughness in the range of from 100 to 250 Sheffieldunits. Bonded to the rough surfaced paper is a photoconductivelayercomprising zinc oxide and in another embodiment sub-millimicron sizedparticles of hydrophobic silica dispersed in a resin binder. The layerconforms to the rough fiber textured surface of the base sheet toprovide a finished recording surface having a roughness in the range offrom 70 to 250 Sheffield units and a gloss (75, Gardner) not in excessof 20 percent. This sheet has the appearance, feel and handle of anuncoated piece of paper.

13 Claims, No Drawings PHOTOELECTROSTATIC RECORDING MEMBER Thisapplication is a continuation-in-part of copending U.S. application Ser.No., 664,958, filed Sept. 1, 1967 and now abandoned.

BACKGROUND OF THE INVENTION:

This invention relates generally to an improved photoelectrostaticrecording member and, more particularly, to a novel copy sheet which,despite being coated, has the general appearance, feel and handle ofordinary, uncoated bond paper.

Known photoelectrostatic recording members comprise a conductive base orsubstrate, ordinarily paper, and a photoconductive layer bonded to andsupported by the substrate. The layer is a resinous substance havingdispersed therein finely divided particles of photoconductive material,such as zinc oxide. Such members are imaged in accordance with the wellknown photoelectrostatic copying process, and developed using apigmented thermoplastic powder that is attracted to the image areas andfixed to the recording surface of the sheet.

In accordance with the conventional method of preparing copy sheets ofthe photoelectrostatic type, the resin material is dissolved in anorganic solvent medium, principally toluene, with photoconductiveparticles of zinc oxide being mixed with this liquid medium until apaint-like consistency is achieved. This mixture is applied as a coatingto a paper base, and the solvent medium is then evaporated leaving athin, homogeneous, photoconductive layer bonded to the support surfaceof the paper base.

In general, conventional copy sheets of this type do not look, feel orhandle like ordinary uncoated writing or bond type paper, and for thisreason have not enjoyed more widespread commercial success.

For example, known photoelectrostatic copy papers have a smoothrecording surface which does not readily receive pencil markings or thelike and tends to be glossy, reflecting illumination in a mirror-likefashion to produce glare. In fact, in the preparation of conventionalcopy sheets, care is taken to insure against producing a rough recordingsurface, since it has heretofore been considered important to havemaximum recording surface smoothness in order to avoid mechanicalentrapment of the developer powder in the background or non-imaged areasof the sheet. Thus, known recording members, although having a surfacewhich does not tend to entrap developer powder, provide a surface thatis somewhat difficult to read and is a poor medium on which to writewith pen or pencil.

Known copy sheets suffer from a further disadvantage in that, as aresult of employing a dense, low-bulk, supercalendered paper base whichenhances the smoothness of the recording surface, the copy sheet,tending to be heavier than ordinary paper, feels limp. Such a sheet doesnot readily lend itself to vertical filing.

SUMMARY OF INVENTION Accordingly, it is the general object of thisinvention to provide an improved photoelectrostatic copy sheet preparedin accordance with organic solvent coating techniques which looks,feels, and handles like ordinary, uncoated writing or bond paper.

It is another object of the present invention to provide an improvedphotoelectrostatic copy sheet which is easy to read being substantiallyglare-free, readily receives pencil markings or the like, and has theaesthetic qualities of bond paper.

It is a further object of the present invention to provide a lightweight, bond-like photoelectrostatic copy sheet prepared in accordancewith organic solvent coating techniques having a semi-rough fiber-typerecording surface which, although rougher than conventional copy sheets,will not mechanically entrap developer powder in background areas.

Contrary to what is generally accepted as desirable, a recording surfacecan have a limited degree of roughness and need not be as smooth asheretofore considered necessary for high quality copy. We havediscovered that a recording surface having a roughness in the range offrom about 70 to 250 Sheffield units and a gloss (75, Gardner) of lessthan 20 percent provides a finish which does not entrap developermaterial and has an uncoated and substantially glare-free appearance.Moreover, even though it has this rough surface a sheet of this type canreadily be converted into a lithographic master that produces excellentprints. Sheets having rough surfaces ordinarily do not function well aslithographic masters. Recording surfaces which have a roughness in therange of to Shefiield units provide even better results.

In preparing a copy sheet having the proper recording surfacesmoothness, two techniques were developed.

a. The first technique calls for applying a zinc oxide resin bindercoating to a paper base having a critical support surface roughness inthe range of from 100 to 250 Sheffield Units. The resinous coating, upondistributing itself over the rough support surface in conformity withthe contours of the fibrous structure of the base provides a recordingsurface which has the same or substantially the same degree of roughnessas the support surface. Thus, a recording surface is formed which issufficiently smooth to avoid mechanical entrapment of the developerpowder, but has numerous irregularities acting to scatter or diffuseincident light rather than reflect the light in an orientated ormirror-like fashion. Resins which enhance or re-enforce the surfaceeffect of light scattering are preferred. The thickness of thephotoconductive layer lies within the range of from 0.1 to 0.5 mil, andis preferably within the range of from 0.2 to 0.4 mil. Microscopicexamination of the recording surface reveals that a layer of thisthickness conforms substantially to the fiber texture of the base.

b. The second technique calls for dispersing in the resin binder, inaddition to the zinc oxide, particles of hydrophobic silica. Whenapplied to a relatively smooth base having a support surface roughnessas low as 40 Sheffield units, a coating containing this type of silicaforms a recording surface which has a roughness of about 100 Sheffieldunits. Preferably, silica/zinc oxide/binder coatings are applied to abase sheet having a roughness in the range of from 100 to 250 Sheffieldunits.

Ordinarily, the addition of silica to a photoconductive coatinginterferes with the photoconductive properties of the sheet. We havediscovered, however, that when hydrophobic silica is added to thephotoconductive coating in small amounts, usually not more than 5percent by weight of the zinc oxide, the photoconductive properties ofthe copy sheet are not impaired, and, surprisingly, print density isgenerally improved. The preferred amount of silica is from 0.2 percentto 1.5 percent by weight of the zinc oxide. If the resin bindercomprises from about 0.1 percent to 10 percent by weight of a siliconeresin, and silica is incorporated into the coating, the surfaceroughness of the copy sheet is further enhanced. The addition of a smallamount of a silicone resin to the binder also improves the performanceof the sheet at high humidity conditions.

A preferred hydrophobic silica is sold by the Pigments Division of theDegussa Corporation of New Jersey under the trade name Aerosil R972.This silica has a very fine particle size of approximately 0.20millimicrons. Treatment of raw silica with an oil or the like inaccordance with standard processing techniques imparts to the R972silica a hydrophobic character. Why this type of silica does notinterfere with the photoconductive properties of the copy sheet is notclearly understood. However, it is believed that because water is notabsorbed by this type of silica, the coating will remain free of thisaqueous contamination which interferes with the electrical properties ofthe sheet. It is clear that the silica must have a hydrophobiccharacter. This is critical. It is believed that the small particle sizemay be important, however, particle size does not seem to be per secritical.

We have also found that, in order for a copy sheet to handle likeuncoated paper, it is necessary for the sheet to be light weight, have ahigh degree of bulk, and have the proper degree of stiffness. Inaccordance with another feature of this invention, an uncalender paperbase having a relatively low basis weight and high degree of stiffnessis employed. Using such a base having the proper support surfaceroughness, a

. copy sheet is provided which handles like ordinary paper.

The following table lists the preferred physical properties, other thanroughness, of the uncoated base as well as the finished copy sheet ofthis invention:

direction Before the base sheet is coated the support surface is usuallytreated'with a solvent holdout precoat, care being taken to insure thatthe critical roughness of the support surface is kept intact. Examplesof suitable precoat materials are: polyvinyl alcohol, starch, casein,animal glue, carboxymethyl cellulose, methyl cellulose, styrenebutadienelatex, acrylic latex, polytetratluoroethylene and algin. The polyvinylalcohol has been found to be especially well suited for this purpose.

The effectiveness of the barrier coating holdout may be tested inaccordance with conventional techniques using an I.G.T. printabilitytester which is manufactured by the Institute of Graphic Techniques,Amsterdam Holland. The I.G.T. tester consists of a pendulum having asector to which a test specimen is clamped, and a printing disc. A testdye solution, applied to the test specimen by means of the printingdisc, is used to stain the specimen. The solution comprises a blend ofthe binder resin, toluene, and lrisol dye (General Aniline and FilmCorporation). The viscosity of this solution is about 14.5 seconds whenmeasuredat 74 F. using a No. 2 Zahn Cup. A drop (0.005 cc.) of thesolution is applied to the disc and the pendulum is permitted to swingfreely. When the pendulum and disc come into contact during the swing ofthe pendulum the dye solution is spread over the test specimen stainingit. The longer the stain on the specimen, the better the holdout. Testresults indicate that the length of the stain must exceed 60 mm. andpreferably should exceed 100 mm.

The photoconductive coating which is applied to the substrate isprepared in accordance with standard techniques. The resin, silica andzinc oxide are blended together in an organic solvent medium and appliedto the support surface using conventional coating equipment. As thesolvent is evaporated, the resinous coating conforms to the fibroussupport surface to form a rough, irregular layer. The coating weight andweight of the base are controlled in order to keep the weight of thecopy sheet in the preferred range of to 25 lbs. per ream 17 inches X 22inches 500 sheets).

A variety of suitable resins are available, the preferred resins being:multipolymers containing vinyl acetate as the major monomeric component,polyvinyl acetate resins, polyester resins, copolymers of vinylchloride-vinyl acetate, phenoxy resins, acrylic resins styrenatedacrylic copolymers and copolymers of styrene-butadiene. It has beenfound that resins containing a polyvinyl acetate component as the majorpolymeric constituent of the resin are particularly well suited for thepurposes of this invention, since they tend to dry to a dull finish,more so than the other resins.

As a result of our discoveries, two types of bond-likephotoelectrostatic recording members are provided:

a. The first type of member comprises a light weight, stifi, precoatedpaper base having a rough support surface, and bonded to the supportsurface a thin, solvent laid photoconductive layer which conforms to therough support surface. The roughness of the fiber textured supportsurface is within the range of from about to 250 Sheffield units,preferably in the range of from to I75 Sheffield units. Thephotoconductive layer comprises. finely divided particles of zinc oxidedispersed in an insulating resin binder. This layer on confonning to thesupport surface provides a recording surface having a roughness in therange of from 70 to 250 Sheffield units.-

preferably from 125 to I75 Sheffield units, and a gloss (75, Gardner)not in excess of 20% preferably in the range of 7 percent to 15 percent.

b. The second type of member comprises a light weight, stiff, precoatedpaper base having either a smooth or, preferably a rough supportsurface, and bonded to the support surface a thin, solvent laid zincoxide/resin binder photoconductive layer containing submillimicron sizeparticles of hydrophobic silica. As a result of the silica, thephotoconductive layer formed on a relatively smooth base has a roughcharacter and low gloss (75, Gardner), i.e., less than 10 percent. Whena layer containing silica is formed on a rough base, an even greaterbond-like surface appearance is achieved.

As a result of the recording surface roughness of the recording member,a copy sheet is provided which greatly resembles ordinary uncoated paperin general appearance, the ability to accept pencil markings, andreading quality.

DESCRIPTION OF PREFERRED EMBODIMENTS The invention is disclosed infurther detail by means of the following examples which are provided forpurposes of illustration only. It will be understood by those skilled inthe art that modifications in barrier coatings, relative proportions ofbinder materials and operating conditions can be made within thedisclosure of this invention without departing from the spirit and scopethereof.

Using such conventional coating means as an air knife applicator, anaqueous solution of polyvinyl alcohol is applied to the support surfaceof the base. A suitable polyvinyl alcohol is sold by the DuPont deNemours & Co., Inc. under the tradename ELVANOL 5105. The base is thendried by slowly passing it through an oven maintained at a temperatureof 200 F. The preferred barrier coating weight is in the range of from0.3 to 0.6 lb. per 3,000 square feet, with the optimum barrier coatbeing 0.5 lb. per 3,000 square feet. Such a thin coating has sufficientsolvent holdout strength to prevent the penetration of the solvent andresin into the base. Since the barrier layer is thin, the rough, fibrouscharacter of the support surface remains intact and is not masked orotherwise materially altered.

(78-3306, National Starch Toluene Methyl Ethyl Ketone The resins,pigments and solvents are milled together for about 1 hour to thoroughlydisperse the pigment particles in the resin, insuring a uniformconsistency. Using conventional roller coating equipment, the paint-likeresinous blend is applied to the pretreated base support surface. Next,the solvent is volatilized at a temperature of about 115 F. leaving onthe support surface of the base a dried photoconductive layer about 0.3mil thick which weighs about 15 lbs. per 3,000 square feet. Thephotoconductive layer has a paper-like finish and the copy sheet islight, weighing 19 lbs. per ream (17 inches X 22 inches 500). This sheethas excellent photoconductive properties and provides a very dense imageon being developed.

EXAMPLE II PAPER BASE SUPPORT:

Bleached Sulfite (West Virginia Pulpand Paper Company) Basis weight(lbs/l 7 inchesXX22 inches 500) Caliper (mils) Roughness of supportsurface (Sheffield units) Stiffness (mg. Gurley) machine direction 100Cross machine direction 50 The support surface is treated as describedin Example I with polyvinyl alcohol.

PHOTOCONDUCTIVE COATING: a

y Weight Polyvinly acetate copolymer 8.l (78-3306, National Starch andChemical Company) Silicone resin (SR82, General Electric Company) 0.3Zinc Oxide (Photox 80, New Jersey Zinc Company) 32.6

Hydrophobic Silica 0.2

(Aerosil R972, Degussa) Tolulene 46.3 Methyl ethyl ketone 12.5

EXAMPLE III This example differs from Example I in the substitution of adifferent type of polyvinyl acetate copolymer, Resyn 26-1404,manufactured by National Starch, for resin 78-3306. The weights, mixingprocedures and coating techniques are substantially the same as inExample II.

EXAMPLE IV This example differs from Example II in the substitution of apolyvinyl acetate terpolymer, 5 912 A manufactured by Midland IndustrialFinishing Company of Waukegan, Illinois,

for resin 78-3306. The weights, mixing procedures and coating techniquesare substantially the same as in Example I]. The member prepared inaccordance with this example performs equally as well as that of Examplell.

EXAMPLE V This example differs from Example I in the substitution of apolyvinyl acetate, Vinac B-l00, manufactured by Air Reduc tion Chemicaland Carbide Company of New York for resin 78-3306. Pure methyl ethylketone is used in place of toluene as the solvent medium.

EXAMPLE VI This example differs from Example II in the substitution of apolyvinyl acetate Daratak 9228, manufactured by Dewey and Almy Companyof Cambridge, Massachusetts, for resin 78- 3306. The weights mixingprocedures and coating techniques are substantially the same as inExample ll.

EXAMPLE VII Photoconductive Coating it y Weight Acrylic resin 33.3

(AT-56, Rohm & Hass) Zinc Oxide (Photox 80, New Jersey Zinc Co.) 6.7Toluene 60.0

The resin, pigments and solvents are blended together as described inExample I and applied in the same manner to the pretreated papersubstrate having a roughness in the range of from to 250 Sheffieldunits. The recording member of this example, upon being developed, hasvery good image density.

EXAMPLE VIII This example differs from Example VII in the of a differentacrylic resin, Bakelite 150, manufactured by the Union CarbideCorporation for resin AT-56.

These materials were blended together as in Example I and applied to therough support surface of the paper base described in Example I.

EXAMPLE X Photoconductive Coating y Weight Phenoxy resin 32.0 (PKHS,manufactured by Union Carbide Company) Zinc Oxide (Photox 80. New JerseyZinc Co.) 4.0 Methyl ethyl ketone 32.0 Toluene 32.0

These materials are blended together and applied to the paper basesupport as described in Example 1.

EXAMPLE XI This example differs from Example I in the substitution of a,styrene-butadiene copolymer, Pliolite CPR 1141A, manufac-; tured by theGoodyear Company, for the polyvinyl acetate copolymer resin. 78-3306. i

EXAMPLE XII This example difiers from Example I in the substitution ofvinyl chloride-vinyl acetate copolymer, VAGH resin, manufactured by theUnion Carbide Company for the polyvinyl. acetate copolymer resin,78-3306. 1

i EXAMPLE Xlll PAPER BASE SUPPORT Bleached Sulfite (Weyerhauser PaperCompany, Fitchburg, Massachusetts) Basis Weight (lbs/l7 inches X 22inches-600) l9 Caliper (mils) 3.9 Roughness of Support Surface 159(Sheffield units) Stiffness (mg, Gurley at 72 F. and 50% relativehumidity) Machine direction 125.2 Cross machine direction 58.2

Using such conventional coating means as a trailing blade applicator, anaqueous solution including polyvinyl alcohol is applied to the supportsurface of the base. The base is then dried by slowly passing it throughan oven maintained at a temperature of about 200 F. The preferredbarrier coating weight is in the range of from 3.0 to 5.0 lbs. per 3,000square feet.

The resin, pigment, etc., are milled together as described in Example Iand applied to the precoated paper base which has a roughness of 159Sheffield units, resulting in a recording surface having a roughness of79 Sheffield units. This sheet has excellent photoconductive propertiesand provides copies with excellent contrast and print density.

The following table lists the physical properties of the novel copypaper prepared in accordance with Examples 1, I1 and X11! standard bondpaper and a typical prior art copy paper. This table, serving as a basisfor comparison, illustrates the marked improvement in paper-likeappearance and feel exhibited by the copy paper of this invention ascompared to the like properties of the prior art material. The resultsof Exam-3 The values in Table II were obtained using well known standardtest procedures with all samples being conditioned at 72 F. and 50percent relative humidity. All roughness measurements were made using aSheffield Smoothness Tester manufactured by the Sheffield Company ofDayton, Ohio, a division of the Bendix Corporation. The smoothness andgloss values set forth hereinabove impart to the copy paper of thisinvention properties, such as a bond-like appearance and feel, similarto those of the standard bond paper. The relatively low gloss value oflack of glare also indicates that the sheet is of a good readingquality. The basis weight, caliper, and pencil take of the copy paper ofthis invention correspond to like properties in the standard bond sheet.The ratio of caliper to basis weight gives an indication of the bulknessof the sheet. As seen from Table II the sheet of this invention having abulk even greater than that of bond paper is far superior to the priorart material. And, although the sheet of this invention is relativelylight weight, it still has the same or substantially the same degree ofstiffness as that of the bond paper.

What is claimed as new and desired to be secured by Letters Bats t thspiteq w 1. A photoelectrostatic recording member having improved visualreadability properties comprising:

1. a paper base support having the following physical characteristics:

a. basis weight (lbs/l7 inches X 22 inches 500) 12-20 h. caliper (mil)2.5-4.0 c. roughness (Sheffield) l25-l75 d. stiffness (mg, Gurley, at 72F. and 50% relative humidity) Machine direction 50-150 cross direction25-100 ing the following physical characteristics:

(a) roughness (Sheffield l25-l75 (b) gloss (75, Gardner) below aboutsaid recording member having a basis weight in the range of from 15 to25 lbs. per (17 inches X 22 inches 500) and a caliper of 3.0 to 4.5mils. v

2. The recording member as defined in claim 1 wherein said layeradditionally includes sub-millimicron size particles of a hydrophobicsilica, said silica being present in an amount not exceeding about 5percent by weight of the zinc oxide.

3. The recording member as defined in claim 2 wherein said resin binderis a mixture of at least two resins, one of said resins having vinylacetate as the major monomeric component and the other resin being asilicone resin, said mixture comprising no more than 10 percent byweight of the silicone resin.

4. The recording member as defined in claim 1 wherein said resin binderincludes a styrenated acrylic copolymer resin.

5. A photoelectrostatic recording member having improved visualreadability properties comprising:

1. paper base support having the following physical characteristics a.basis weight (pounds per 17 by 22 inches 500 sheets) ples i, ii, andXlll are representative of all the examples. 1 65 v TABLE II StandardExample Example Exam 1e Prior bond paper I 11 X II art Basis weight(lbs./17 inches x 22 inches-500) 14-25 21. 2 24.0 25. 6 30 Caliper(mil.) 2. 0-4.0 3. 7 3. 9 4. 2 3. 8 Roughness (Shefileld).. -250 149 10079 45 Gloss (75, Gardner)... 5-10 6-6 5-6 18.9 31 Caliper/basis weight..143-. 176 162 164 127 MD stiffness (mg. Gurley 100400 126 160 176 136 CDstifiness (mg. Gurley) 60-125 82 93 109 107 Pencil take 1 Excellent. 1Poor.

prising a resin binder having a finely divided photocon-,

ductive zinc oxide and sub-millimicron sized hydrophobic silicaparticles dispersed therein, said silica particles being present in anamount not exceeding about percent by weight of the zinc oxide, andhaving the following physical characteristics:

a. roughness (Sheffield) 100-250 b. gloss (75, Gardner) below about 10percent said recording member having a basisweight in the range of fromto 25 pounds per (17 inches by 22 inches 500).

6. The recording member as defined in claim 5 wherein the layer has athickness in the range of from 0.1 to 0.5 mil.

7. The recording member as defined in claim 5 wherein the particle sizeof the silica is about 0.20 millimicrons.

8. The recording member as defined in claim 5 wherein said paper base istreated with a solvent barrier precoat to render said support surfaceresistant to the penetration of organic solvents, said precoat beingselected from the group consisting of polyvinyl alcohol, starch, casein,animal glue, carboxymethyl cellulose, methyl cellulose,styrene-butadiene latex, acrylic latex, polytetraflouroethylene, andalign.

9. The recording member as defined in claim 5 wherein said resin binderis selected from the group consisting of multipolymers containing vinylacetate as the major monomeric component, polyvinyl acetate resin,polyester resin, copolymers of vinyl chloride-vinyl acetate, a phenoxyresin, acrylic resin, and copolymers of styrene-butadiene.

10. A photoelectrostatic recording member having improved visualreadability properties comprising:

l. a paper base support having the following physical characteristics:

a. basis weight (pounds per 17 inches by 22 inches 500) b. caliper(mils) 2.5-4.0

c. roughness (Sheffield) about 55 d. stiffness mg., GurleyQat 72 F. and50 percent relative humidity) machine direction 50-150 cross direction25-100 5 2. a barrie coating applied to said base support providing asolvent hold-out in excess of 60 millimeters;

3. a photoconductive layer covering and bonded to said base supportcomprising an organic laid coating a finely divided photoconductive zincoxide and sub-millimicron sized hydrophobic silica particles dispersedin an insulating resin binder containing from 0.1 percent to 10 percentby weight of a silicone resin, and having the following physicalcharacteristics:

a. roughness (Sheffield) about 100 b. gloss (75, Gardner) below about 7percent said recording member having a basis weight in the range of from15 to 25 pounds per (17 inches X 22 inches 500) and a caliper of3.0 to4.5 mils. 11. The recording member as defined in claim 10 wherein theremainder of said resin binder is a resin having polyvinyl acetate asthe major component.

12. A photoelectrostatic recording member having improved visualreadability properties comprising:

1. a paper base support having the following physical 25characteristics:

a. basis weight (lbs./l7 inches X 22 inches S00) l2-20 b. caliper (mils)2.5-4.0 c. ro ghness (Sheffield) 150-250 d. stiffness (mg, Gurley at 72F. and 50% relative humidity) Machine direction 50-150 Cross direction25-100 2. a barrier coating applied to said base support providing asolvent holdout in excess of 60 mm; 3. a photoconductive layer coveringand bonded to said said recording member having a basis weight in therange of from 15 to 25 lbs. per (17 inches X 22 inches 500) and caliperof 3.0 to 4.5 mils.

13. The recording member as defined in claim 11 wherein said resinbinder includes a styrenated acrylic copolymer resin.

I II 3

2. The recording member as defined in claim 1 wherein said layeradditionally includes sub-millimicron size particles of a hydrophobicsilica, said silica being present in an amount not exceeding about 5percent by weight of the zinc oxide.
 2. a barrier coating applied tosaid base support providing a solvent hold-out in excess of 60millimeters;
 2. a barrier coating applied to said base support providinga solvent holdout in excess of 60 mm;
 2. a barrier coating applied tosaid base support providing a solvent holdout in excess of 60 mm; 2.said base support providing a solvent hold-out in excess of 60millimeters;
 3. a photoconductive layer covering and bonded to said basesupport comprising an organic solvent laid coating of zinc oxidedispersed in an insulating resin binder having the following physicalcharacteristics: a. roughness (Sheffield) 70-150 b. gloss (75*, Gardner)below about 20% said recording member having a basis weight in the rangeof from 15 to 25 lbs. per (17 inches X 22 inches - 500) and a caliper of3.0 to 4.5 mils.
 3. a photoconductive layer covering and bonded to saidbase support comprising an organic solvent laid coating of zinc oxidedispersed in an insulating resin binder having the following physicalcharacteristics: (a) roughness (Sheffield 125-175 (b) gloss (75*,Gardner) below about 7% said recording member having a basis weight inthe range of from 15 to 25 lbs. per (17 inches X 22 inches - 500) and acaliper of 3.0 to 4.5 mils.
 3. a photoconductive layer covering andbonded to said base support comprising an organic laid coating of finelydivided photoconductive zinc oxide and sub-millimicron sized hydrophobicsilica particles dispersed in an insulating resin binder containing from0.1 percent to 10 percent by weight of a silicone resin, and having thefollowing physical characteristics: a. roughness (Sheffield) about 100b. gloss (75*, Gardner) below about 7 percent said recording memberhaving a basis weight in the range of from 15 to 25 pounds per (17inches X 22 inches - 500) and a caliper of 3.0 to 4.5 mils.
 3. Therecording member as defined in claim 2 wherein said resin binder is amixture of at least two resins, one of said resins having vinyl acetateas the major monomeric component and the other resin being a siliconeresin, said mixture comprising no more than 10 percent by weight of thesilicone resin.
 3. a photoconductive layer covering and bonded to saidbase support comprising an organic solvent laid coating comprising aresin binder having a finely divided photoconductive zinc oxide andsub-millimicron sized hydrophobic silica particles dispersed therein,said silica particles being present in an amount not exceeding about 5percent by weight of the zinc oxide, and having the following physicalcharacteristics: a. roughness (Sheffield) 100-250 b. gloss (75*,Gardner) below about 10 percent said recording member having a basisweight in the range of from 15 to 25 pounds per (17 inches by 22inches - 500).
 4. The recording member as defined in claim 1 whereinsaid resin binder includes a styrenated acrylic copolymer resin.
 5. Aphotoelectrostatic recording member having improved visual readabilityproperties comprising:
 6. The recording member as defined in claim 5wherein the layer has a thickness in the range of from 0.1 to 0.5 mil.7. The recording member as defined in claim 5 wherein the particle sizeof the silica is about 0.20 millimicrons.
 8. The recording member asdefined in claim 5 wherein said paper base is treated with a solventbarrier precoat to render said support surface resistant to thepenetration of organic solvents, said precoat being selected from thegroup consisting of polyvinyl alcohol, starch, casein, animal glue,carboxymethyl cellulose, methyl cellulose, styrene-butadiene latex,acrylic latex, polytetraflouroethylene, and align.
 9. The recordingmember as defined in claim 5 wherein said resin binder is selected fromthe group consisting of multipolymers containing vinyl acetate as themajor monomeric component, polyvinYl acetate resin, polyester resin,copolymers of vinyl chloride-vinyl acetate, phenoxy resin, acrylicresin, and copolymers of styrene-butadiene.
 10. A photoelectrostaticrecording member having improved visual readability propertiescomprising:
 11. The recording member as defined in claim 10 wherein theremainder of said resin binder is a resin having polyvinyl acetate asthe major component.
 12. A photoelectrostatic recording member havingimproved visual readability properties comprising:
 13. The recordingmember as defined in claim 11 wherein said resin binder includes astyrenated acrylic copolymer resin.